Presently known are ultrasonic testing methods for solid materials, such as metals, weld joints, or composite materials which may be evaluated by ultrasonic testing methods in order to determine their relative density; such testing methods are substantially limited to establishing the physical strength of such materials. Such solid materials however are ones which have a density and/or other physical characteristics which do not appreciably change during their service life.
Electrical devices, including electronic devices, are ubiquitous. Such devices rely upon power sources for their operation and increasingly, such electrical devices rely on one or more electrochemical cells, hereinafter referred to as a “battery”. Batteries are found in portable devices (i.e., electronic devices including telecommunications devices including cell phones, computers, tablets), vehicles (i.e., aircraft, automobiles, boats, etc.) as well as in non-portable applications (i.e., power supplies, backup batteries for mains powered electrical devices). The proliferation of such devices is expected to increase in the indefinite future, and with it the use of batteries to power such devices. Such batteries may be of any variety of chemistries and/or configurations, the only requirement being that they can be used as a power source for electrical and/or electronic devices. Presently, common battery types include so-called “wet cell” lead-acid batteries containing a liquid electrolyte which are still often found in high amperage applications, such as in automobiles, backup batteries and power supplies, as well as in alarm systems. Of growing prevalence are so-called “dry cell” battery types which include a non-liquid electrolyte, with the most common types being rechargeable nickel cadmium (NiCd) and nickel metal hydride (NiMH) type batteries, rechargeable lithium-ion (Li-ion) batteries including Graphite/LiNMC and Graphite/LiNCA type batteries, and non-rechargeable Zn—MnO2 (alkaline) type batteries. The latter non-liquid electrolyte type batteries find prominent utility in vehicles as well as in portable electrical and/or electronic devices, and are available in a plethora of configurations. Most are either characterized as single-use type batteries intended to be disposed after discharge, or rechargeable type batteries which can be recharged, and are used a number of times.
With the increasing use of such batteries, and their widespread presence in devices, vehicles, etc., there is a growing need for methods of monitoring the performance characteristics of these batteries. Two such performance characteristics include a “state of charge” (SOC) of the battery, which is related to the amount of current which may yet be supplied by the battery in its particular state, and “state of health” (SOH) of the battery, which is related to the overall physical state of the battery and/or its performance characteristics. Such performance characteristics may include predicted performance characteristics, as well as actual performance characteristics.
Present methods for determining the SOC and/or SOH of a battery usually require an invasive technique which may either degrade or destroy the battery, or require that the battery be discharged when seeking to determine the SOC and/or SOH. Such techniques are frequently impractical; the best case scenario requires depletion of some of the battery charge while providing little information concerning the internal construction features of the battery, and in the worst case scenario the battery under evaluation is incapacitated or destroyed and cannot be reused. One recently proposed technique and apparatus is the mechanical measurement technique and apparatus disclosed in US 2014/0107949 describing the use of a load cell and a stress/strain sensor mechanically coupled to a battery, and used to determine mechanical battery and/or cell expansion. The apparatus is useful in measuring the stress as well as the strain which is stated to be relevant to the SOC and the SOH of the battery. However, the technique provides little information regarding the physical state of the internal components or parts of the battery, e.g, anode, cathode, separator layer(s), merely from the stress and/or strain readings provided. The technique also requires the removal of the battery from the device in which it is installed, and subsequent placement within the disclosed apparatus for measuring stress and strain.
Accordingly, there exists a real and urgent need in the art for an improved method, apparatus and system for determining the SOC and/or SOC of a battery. There also exists a real and urgent need in the art for a noninvasive technique for evaluating the physical state of one or more internal components or parts of a battery.